2.2. Synthesis of Dimethyl 2,5-Furandicarboxylate Monomer

The synthesis of DMFDC followed a previously reported procedure [3]. Typically, DMFDC was prepared by reacting FDCA with an excess of methanol, under acidic conditions (HCl), at 80 °C for 15 h. The final product was isolated in 71% yield as a white powder. FTIR (ν/cm⁻¹): 3168 (=C–H); 2965 (C–H); 1706 (C=O); 1578, 1522 (C=C); 1288 (C–O); 1024 (furan ring breathing); 969, 825, 757 (2,5-dibustituted furan ring). ¹H NMR (300 MHz, CDCl₃, δ/ ppm): 7.2 (s, H3/H4 furan ring); 3.9 (s, 2,5-COOCH3). ¹³C NMR (75 MHz, CDCl₃, δ/ppm): 158 (2,5-C=O); 147 (C2/C5 furan ring); 118 (C3/C4 furan ring); 52 (2,5-COOCH₃).